More specifically, this invention relates to a dispenser generally consisting of a substantially cylindrical hollow containment body insertable into the neck of a bottle.
The containment body is connected to a threaded ring nut which is screwed to the neck of a bottle.
More specifically, the containment body comprises an annular portion which faces an annular portion of the ring nut and connected thereto.
At a first end of it, the containment body has an inlet orifice for the liquid in the bottle. The orifice is opened or closed by a ball which is free to roll inside the containment body, in particular inside a dispensing chamber included therein.
The dispensing chamber is defined by the space between a piston, guided by a hollow stem slidable inside the containment body, and the bottom portion (where the orifice is) of the containment body.
Between the piston and the stem there are means for opening and closing the hollow in the stem in such a way as to selectively place the inside of the stem in fluid communication with the dispensing chamber.
The movement of the stem is guided by a retaining ring attached to the containment body which also serves the function of piston limit stop.
In other words, the retaining ring defines the upper limit of the dispensing chamber, preventing the piston from coming out of the dispensing chamber.
When the piston creates an overpressure inside the dispensing chamber, the hollow in the stem is in fluid communication with the dispensing chamber and the fluid in the dispensing chamber rises along the stem and is delivered through a spout associated therewith.
In this configuration, the ball is in the lowered position and occludes the orifice.
When the piston creates a negative pressure inside the dispensing chamber, the hollow in the stem is not in fluid communication with the dispensing chamber and fluid is sucked into the dispensing chamber from the bottle.
In this configuration, the negative pressure in the dispensing chamber causes the ball to rise, leaving the orifice open.
In this type of dispenser, the piston is made to slide inside the containment body by opposing the action of a spring whose function is to keep the stem and the piston connected thereto in the raised position.
More specifically, by applying a compressive action on the stem, the piston slides in the dispensing chamber, reducing the size of the chamber and thus creating an overpressure inside it.
When the compressive action on the stem ceases, the spring takes the movable stem/piston assembly back to the raised position, increasing the size of the dispensing chamber and thereby creating a negative pressure in it.
The pressing action on the stem is exerted on the delivery spout located at the upper end of the stem and in fluid communication therewith in order to deliver to the outside atmosphere the liquid contained in the bottle.
At each delivery, a volume of air equal to the liquid delivered must enter the bottle in order to keep the balance of pressure between the inside of the bottle and the outside atmosphere.
For this purpose, prior art dispensers have a fluid inlet between the fastening ring nut and the dispensing spout connected thereto, that is to say, a passage through which air is allowed in so that air from the outside atmosphere can flow into apertures made inside the containment body.
More specifically, these apertures guarantee that the air drawn in between spout and ring nut can reach a hole made in the outside surface of the containment body inside the bottle.
These apertures place the outside atmosphere in fluid communication with the aforementioned hole when the piston is in the lowered position, that is to say when the piston is rising inside the dispensing chamber.
That way, the liquid sucked out of the bottle and into the dosing chamber is replaced by air drawn into the bottle.
When the piston is in the raised position, the apertures occlude the fluid communication between the outside atmosphere (that is to say, between the air inlet passage) and the inside of the bottle (that is to say, the hole made in the containment body).
The prior art dispensers described above have some disadvantages.
In particular, under falling water—for example in a shower—the top of the dispenser (that is, the part with the spout), which is directly exposed to the falling water, is covered by a film of water.
Thus, when the dispenser is operated, water is drawn into the containment body, in addition to air, through the passage between the spout and the ring nut.
The water that enters the containment body follows the same path as the air and, through the apertures, finds its way into the bottle, where it mixes with the liquid contained in the bottle.
This dilutes the liquid in the bottle which, after prolonged use of the dispenser, may become heavy and unacceptable.
Also known are dispensers which can overcome the disadvantage just described. These dispensers have protuberances which keep the inside surface of the ring nut spaced from an annular shoulder of the containment body. More specifically, the ring nut has an annular portion positioned to face the shoulder of the containment body from above. That way, the protuberances define a series of air passage channels designed to place the outside atmosphere in fluid communication (through the threaded inside surface of the ring nut) with the hole made in the outside surface of the containment body inside the bottle.
This minimizes water entry when the dispenser is used under falling water because the inlet passage which places the hole in fluid communication with the outside atmosphere is not directly exposed to the falling water.
Also, the slidable coupling between ring nut and delivery spout may be made in such a way as to reduce or even eliminate entry altogether.
Dispensers of this kind, too, are not free of disadvantages, however.
In effect, it should be noted that in this case the ring nut, which is made as one piece, is not very adaptable to the surface of the delivery spout. That means the coupling between the ring nut and the spout may in some cases be poorly sealed and in others, excessively stiff on account of high friction between the two parts.
Moreover, excessive expansion of the external sealing washer on account of over-tightening the ring nut obstructs the air inlet path, making it difficult for the replacement air to flow into the bottle.